Vibrational spectroscopy and quantum mechanics calculations of nitric acid chemisorbed on γ-Al_O_3 and TiO_2

摘要

Nitric acid chemisorbed on components of tropospheric aerosols such as TiO_2 and γ-Al_2O_3 can form several coordination structures and undergoes photo-induced removal in overall proportions of (20 ± 3) % and (30 ± 2) %, respectively. However, the loss of chemisorbed nitrate from the surfaces will depend not only on the surface but also on the structure of the chemisorbed nitrate. Upon irradiation, the chemisorbed nitrate bridging structure on TiO_2 is removed from the surface in a higher proportion than the monodentate structure. However, the photo-induced nitrate removal from γ-Al_2O_3 does not show a clearly favored coordination structure, as both structures modeled seem to be removed in a more equivalent proportion than that observed for TiO_2.